The present disclosure relates to a power saving technique for an image forming apparatus.
Equipment (image forming apparatus) such as a multifunction peripheral or a printer may have a normal mode and a power saving mode. The power saving mode is a mode for saving power in a non-use state (standby state). In the power saving mode, the number of portions supplied with power in the system is reduced to be smaller than that in the normal mode in order to reduce power consumption. Therefore, functions of the equipment cannot be used in the power saving mode. In order to use the equipment, it is necessary to restore the equipment to the normal mode so as to restart power supply to the individual portions. Further, as to equipment connected to a network, the equipment may be maintained in a communicable state also in the power saving mode, and a specific bit pattern (wakeup packet) may be sent to the equipment in the power saving mode so as to restore the equipment from the power saving mode to the normal mode by network communication.
For instance, there is known equipment having a power saving state, a normal state, and a power saving function, in which restoration from the power saving state to the normal state is performed based on an input frequency of a signal including a specific bit pattern. In this structure, not only a condition that a wakeup pattern has been received but also a condition that the number of wakeup patterns received per unit time is a predetermined threshold value or larger is used as the condition for restoring from the power saving state to the normal state. In this way, the requirement to maintain the power saving state of the equipment is prioritized to the requirement to use the equipment.
As described above, the image forming apparatus has the normal mode and the power saving mode. In the power saving mode, power supply to a part of the system such as a printing portion for executing a job may be stopped. On the other hand, even in the power saving mode, in order to maintain a minimum function, power may be supplied to a circuit or a substrate such as a communication portion for receiving a request or information from the network and a controller for performing a process to be performed even in the power saving mode (for example, a process concerning communication).
Specifically, as for the controller, it is necessary to regularly perform a process to be performed every constant period by control software such as an OS of the image forming apparatus or a process concerning a network communication response even in the power saving mode. Therefore, power may be temporarily supplied to the controller for performing a necessary process even in the power saving mode, and afterward the power supply to the controller is stopped. In other words, even in the power saving mode, the controller may be started to be temporarily restored.
Here, there are standards concerning power consumption (power saving) of the image forming apparatus in USA, Japan, Europe, and the like. For instance, there are standards such as Energy Star. In these standards, it is necessary to suppress power consumption of the image forming apparatus even in the power saving mode. Therefore, in designing the image forming apparatus, a target or a specification concerning power consumption of the controller during the power saving mode is set considering the standards. In order to achieve the target and the specification, an operation and power consumption of the controller in the power saving mode are designed in view of a hardware aspect and a software aspect.
However, when controller is temporarily restored every time when a request to communicate is received from the network, a frequency of the temporary restoration of the controller is increased. When start and temporary restoration of the controller are performed frequently during the power saving mode, average power consumption of the image forming apparatus during the power saving mode is increased. Therefore, when the controller is frequently restored during the power saving mode, a target, a specification or a public standard concerning power consumption of the controller during the power saving mode may not be satisfied with high possibility.
Here, the above-mentioned technique for restoring to the normal mode by the wakeup pattern is not a technique concerning start and restoration of a circuit or a substrate such as a controller in the power saving mode. Further, it is necessary to perform the process including determination process of the wakeup pattern by a communication substrate for performing a process concerning network communication during the power saving mode. Therefore, the structure is apt to have a relatively large scale so that the power consumption is increased. Then, there may be a case where power consumption of the image forming apparatus in the power saving mode cannot be reduced.